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Could the planet recover from climate change?

Research from the Department of Earth and Planetary Sciences’ Dr Philip Pogge von Strandmann found the Earth’s ‘natural thermostat’ could enable recovery from climate change – but this would take hundreds of thousands of years.

New research indicates that the Earth has a ‘natural thermostat’, which could enable the planet to recover from the extremes of climate change – but that the time this recovery could take is significant.

The team, led by Birkbeck’s Dr Philip Pogge von Strandmann, found changes in the rate of weathering rocks – the main mechanism for removing CO2 from the atmosphere – associated with global cooling events. The more weathering, the more CO2 is removed from the atmosphere.

Weathering can cool the Earth in warm periods and takes place at a slower rate during cold periods – supporting the idea of an ‘Earth thermostat’ regulating the planet’s temperature.

Using samples of rocks from Anticosti Island (Quebec, Canada) and Dob’s Linn (near Moffat, Scotland), the team were able to demonstrate how the global chemical weathering rate declined significantly during the 5°C cooling that caused the Hirnantian glaciation around 445 million years ago, which in turn led to the second greatest extinction of life in history. This meant less CO2 was removed from the atmosphere, and the climate was able to recover.

Speaking of the findings at the Goldschmidt Conference in Paris, Dr Pogge von Strandmann explained: “We were able to confirm that chemical weathering is the driver of the Earth’s natural thermostat. When there is a warmer climate, there is more weathering, and when it is cooler there is less weathering: this is what you would expect, given that chemical reactions go faster with increasing temperature. So more weathering removes CO2 from the atmosphere and puts a brake on global warming. However, when the temperature cools, the reverse is true, and less CO2 is removed from the atmosphere in cold periods. This is the process that has allowed life to survive on Earth for around 4 billion years.

“Nevertheless, we need to be clear that the changes in temperature are gradual, and that recovery can take hundreds of thousands of years. Given the rapid increase in the rate of global warming at present, this kind of wait is not an option for us.”